SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3f8f53dbf3237f9abe2bc3a276c28f553da806fbeeb42408f5130a36479f564' 
  AND token = 'LCPgGCPp8LzcGswfOrGQhOMUJCrMsQ1t/X518fhn3NQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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