SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87ef0e12785212a93dbf7b3f5ba452e1b54f9f68670b9ad640e3f622f6bbd973' 
  AND token = '8j7iLW+PKXIcYmbecY++kXZkEj0+kubk6GRilFhXTO0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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