SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c52fae92897f8942d5b90199890806bce54b81100531da82dd77457d6df59951' 
  AND token = '1DGEj1gToOooJ3/Zvkyg3fJoJoVJxxF9p1sgF2UFVKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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