SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9ec709f84bcc9e307dfce3b895cfc73a2d52cc4a96fe93b4160e3f58b942910' 
  AND token = '+duHdvHaZHpJvhnz9rQInZCKagNaNCOgqleLKfCbNss=' 
  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"
    }
  }
}