SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c120c2aaec3afa8919ecdf2ef6c19183e90d3f4b83d52ec7e50fd7a328fe3e41' 
  AND token = 'lOUv351Es0qgRfg4j9NMDiXupJBMviW9x8dQ6XS1LwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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