SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e998e0d13e6e2cfa4f35282862aaee2dd9113889131126ec300649c230645f9d' 
  AND token = 'B09axxwb2/GDLEK2SfyWbaiwX+vdnFrvB0ZNTP0UMrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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