SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '248f903f2e0657cd424e66772fc6ec7e38307943c6570d4b0bded7a5d670eda4' 
  AND token = '+AZTAjumMwEqJc3Mryd1DYeOlsaiWXB6AJBupBtCIFw=' 
  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"
    }
  }
}