SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34b23158217662e749969e09146be1d6c5066aada5583b49f7f870a402f507bf' 
  AND token = 'fNty78Ecot+zwRMtNVJqvwp2yj1APkFKhI3/BItslhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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