SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8494f46c5b40827d17acd2cff94f3d09659c895ba2d7d46aede26087afc5c8e' 
  AND token = 'uJ7rMqWcOQKliWWg+PtWP2aPTbz1KQ+kKDXyYJ9dvsQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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