SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1363df66bb255065ef4b18d647c1f6778511c556820213845e387bd654630bc' 
  AND token = 'fr2ctJKYQIWSqTLwOu/jGHds38XJIvBREFrqFTj+9Ag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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