SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0ce0f08df6f287954fe3e9ce6db7dbdf06a32e9b8a6868e34738d33d8835ec2' 
  AND token = 'hbmEcbFpzL31pnuNKLpMXBZ0+bcnZVbquxwxJBhouoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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