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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bde2d4f3bf9e3aa2df5445b4daa79a5d867ab1c468375a1e43de2fdc6052f661' 
  AND token = 'SqFNzon3LNwW8PQ+mp1tpXWTSYQ9HLEIXVqXEckpPvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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