SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '768ffc6fe4fc821bbc8cc6ee54d6c44c38e487d9fa387ddcfc435852ba837cff' 
  AND token = 'aKjJD+Q+6z7KbaQRe/DzjdDdtsvz1MqbXowG43g9Fow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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