SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adcaa19960e88951410ad847f600fdbbf47835b6d5a563181802e0e928144d66' 
  AND token = 'qpghcRtUHWKT8b7n7VIiJzVQGt1+qVt4AHwvj0WVrhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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