SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ef92a8a50d8a71d91b39643b53c42c9d8bf6566bf4ea544e37fb8eb8a39f437' 
  AND token = 'srVCZAbnCFslULbMudxxmhkEtCFDAqksg2rUIPncK6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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