SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2878ba6e4add65c9d71555568db199057f4145400c7ca0d91c35533577dc77c' 
  AND token = 'rHcYLUm86bZuQN77WySyBI1E/F2yju09QwHg3oxcpZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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