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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a78e4cf1ba1d78cd3acbdc659c72615adc68c5c38ecf28b8e4ac3e302b50a6eb' 
  AND token = 'qgkSvas6BNe8mL+ibSJiLNGghid4371VZeA4i9DPaqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}