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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6c1a17903c14bfa4fdc279edd639783a4059c9bd3c6aa8c077a3f2d3e31d45c' 
  AND token = '+3t8ahJopFBnBbKGEAP4n9qj7kkjGUaZ/ijo0tvbBEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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