SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '858f86e2eba4b7689b80952e4e96379847de385988d0c545990cfe2f110d4e43' 
  AND token = 'cHqMcBqlVorBOt1eTPGKw2JXIQxjnPEaQwDABv9igtY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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