SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b8c7ce65f1849e9f7d32f27419626a50405a2f3083ee74e262a054fe053df58' 
  AND token = 'PyWh2hvq12tkWZ+SRVx429tqyYj/AKxpsxOTjyZ7BBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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