SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbf7ab7cfd387a62e516e450db074187bd736037b2b286f3c76d1c178f287939' 
  AND token = 'X5lIv64kf+aQFV9CUbNmolwNN5GQQvUIsFtHTbKohBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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