SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9f9abc34843a4509ecda02fdd05856e6cace2a34f07bd07b0b98e741212a134' 
  AND token = 'B2LpY9BPHSX7fYfX4nmNojzgT4pyfyLNVCfIJQR61/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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