SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e646cc97266234c1dad6b45cffbd34fcfd5295c92c129053cb0de20f3a19ac53' 
  AND token = 'UpdHdBWYgTOp12N9L2GemWti3T9c7BMqJQEDVPiza/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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