SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b8fb6d099be7d136cd58dea2ad375dc2c8f49b081ab5906b774a5d94f2774e07' 
  AND token = 'jIurnFgks3kRHQCP6O/MY7qUkg+PSfgwdaOIiYPUpEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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