SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '627a916e5f10bab673131c755cd99e084a038ef978c95e0a23a28843e29717ef' 
  AND token = 'RFNGlmql5jYHgrNy4kV63ZHfdtLEoQDM8nvYv+waMTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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