SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6d359e329d06a1024e5cddec3160ec06313b95458ea1c583e3c48374269d136b' 
  AND token = 'JLrQR2VoYKZphceOpnp4YLIVaDt9tZnJKwEPzDIFk9k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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