SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6e8171187acba1acd2519d36b09f125ef6753cdf4364422981d5db5c3372eb3' 
  AND token = 'wsiaCzl6OTvK3qILzAbWR2OTLmXhnFjG5M748AuVNT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00075

JSON explain

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