SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7df3b6c57deaafe0d110e296053b1dbedd3572cf11aff46dab81ac2e746a5d72' 
  AND token = 'k0yWa54BTFVcPe4lHkH+BLlDGRv9Rl/yE4f6Evu/o+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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