SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b6941a4bb1a748f940e31dccbe0be2c56bdd9a64521b5d86b63f8f0cc9fd5a5' 
  AND token = 'nykXNFyBTv8UuHutECoTUhMoGEaQR5Q9slZ1L2iYhR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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