SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36c781ef856f5c88a1fa8378328486e7d94c851deddfc851710c49dab9a81ae3' 
  AND token = 'DLhAaAzieAJD6Qx3/pdDFhSIgEeE3dyymVmlvpbma/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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