SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '4d5a554b5e397d8a7a1366fc54c73c5973e22217b65cdbc7c36270a03b183e8c' 
  AND token = 'ur1hzrd9d71aRR9VE64Xk210m3eo/BGAActXElTKMx0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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