SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75168e24c84adda2aea1480ecd536a30dced522ea43e88c5f3a1ab7965952aa6' 
  AND token = 'rD6WJHqXe5ykK2thT2qrHjFRfVklVlRXTHtdy6XXGHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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