SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fb779495a960a09345fff5a0470fbaae8968594abfa48757f0dca27f60a92cf' 
  AND token = 'zSDqwzCzjZXe3zpxAL8TXDs+kzbZiigar4Jjq2hiksc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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