SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6bb8281f1220e94a09cc7ff85b4ae09dcb90747d4286b39e24e30a5683d67ae5' 
  AND token = 'CR5KZwwZqE4z1ojmXSE/SZUV7pz9GDHDMZ40lum2rjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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