SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c9f0f36767ad36b1543b442c182b5427fd9e1792e210d532494cb2e93a396b8' 
  AND token = 'PhC2VofddCvidCkgTALjqmoX4UCJ7jBnS9ajazD7Yyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}