SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d50a5dfa5c4f7adad3b210387a20244ba0592763b389001941f482bbd402da8' 
  AND token = 'xhiqW3BryHIOQbMc8M0KEUlGXI+Y98x+Uk4Fh1nGSPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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