SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'd4b2c86172a45354c658323eede3c021b37a8291f65dfb7bab738b84195678c1' 
  AND token = '39gMESBi/N0CwAjZVgAcrMrljyGIYc51ykou9tzFkz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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