SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35b43bc91147f2e85c83e29d09db25ceae7f337f8beba97539bc73c442fec776' 
  AND token = 'sy+14iHvGS2EOz2t+lnURmUwwcFBxFV3IJJTHzes/Bo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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