SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6947cda297e6e3a29e100e3576191691765cd749f2d9d9d5e316c0e33bc5a694' 
  AND token = 'Duf+Wh1udvGnIT2Y5RiT6aoD/xFarZBvKiAcFjN6P84=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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