SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f999341e217340a919ff7230070e8340396648a2305cedd05c542e8d0ddac76' 
  AND token = '4p/++0hfPi5MnEQ2PRf2h8BuoqMIRg++kokUFPeXpww=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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