SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '408390416752180e734f332ce37f321221e2486ae1fa96a78b5c460f6dab0b51' 
  AND token = 'rdM2HEHBvZht+ZwIVm2vgdz001y/VduQfbYz436QDhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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