SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b6811beb2da01a54d4321014d222d07e16ff24a1caf3372aa8d0eeb6b1aa265' 
  AND token = '8EnmtgQBLXWNAekZvKdRyvhFpcTeI2hcvrxixvi7u6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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