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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da1b6c6d59b9d7779616fc68093b6dbb40c5afd9932fc873267164de1d18d0ab' 
  AND token = 'nj3ZmOKm4qfoXzq6DC4tkw/CVB/oVB7eHbTcWN6pAuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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