SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a625877873f746420e3b6647eea7435ac4031c9896990767f353d41e4c7fb4cb' 
  AND token = 'LhtTtAlsXzvyltnlxe5yM/xJy4fhmsaBL6CeI8/Xpjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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