SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'dd3467328eacf3cc2abdbf5b96e9fbe10479e2036144e0e99193670feeb3bb5a' 
  AND token = 'iV0XMDNCf1YCsRJ2iqr8joiBEeMLsKT7+CuzB2EJAk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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