SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b975567fe66010e44032d7616644ae129d411250536f15686428d984b21b2ce3' 
  AND token = 'cBftirSNyAnAN0qwwWvp/f52/lsdr5in5+07TZFqwnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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