SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0743f0777c6bd18aef989cb6d54198eb70c193a52255dbfe74b810b35c301c0' 
  AND token = 'n93ZrgUMdlr0nIiikujmPZcgAP1EEMWZTom60JAtiMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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